Elliptical Trigonometry

Another math teacher here at Scattergood asked me at dinner, “What about trigonometry on other shapes, like ellipses?”  We know about hyperbolic cosines, but what about other things?

I whipped up this geogebra applet.  There are 3 green points you can find and drag – make sure you play with all three, because they’re pretty cool!

Sorry, the GeoGebra Applet could not be started. Please make sure that Java 1.4.2 (or later) is installed and active in your browser (Readers don't work: Click here to go directly to the post online)

Riley Lark, Created with GeoGebra

I didn’t go to the trouble to make this one interactive, but here’s a square cosine wave:

5 thoughts on “Elliptical Trigonometry”

  1. Very interesting – I particularly like your use of the ‘locus’ tool, which people often find quite mysterious. It would interesting to try to derive cartesian equations for some of your elliptic sines/cosines.

    On another topic, I see you have picked exactly the same WordPress theme as me — got me very confused when I clicked on the link: ‘I don’t remember writing this…’!

  2. Thanks for the comments, guys – I really like geogebra, and I think it’s a vital tool for math teachers. What else is so powerful but easy enough for students to learn?

    I’ll be happy to detail answers to any geogebra questions I can answer!

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